Valve construction

ABSTRACT

A condition responsive pneumatic valve construction having a support means provided with a valve seat means. A plural leg ambient temperature compensating bimetal member has one of the legs thereof provided with a free end means that controls the valve seat means in response to radiant heat directed to such one bimetal leg through an aligned window means in a cover means carried by the support means, the remainder of said legs being secured to said support means at the free end means thereof.

, United States Patent Scott [54] VALVE CONSTRUCTION [75] Inventor: Douglas R. Scott, Knoxville, Tenn.

[73] Assignee: Robertshaw Controls Richmond, Va.

[22] Filed: Jan. 4, 1971 [21] Appl, No; 103,704

Company,

Related US. Application Data [63] Continuation-in-part of Ser. No. 815,977, April 14,

[52] US. Cl. ..236/87, 137/82, 251/357, 337/99, 337/379 [51] Int. Cl. ..G05d 23/27, G05d 23/275 [58] Field of Search ..236/83, 87, 68 R; 337/379, 337/99, 378; 251/11, 357; 137/82, 525.3

[56] References Cited UNITED STATES PATENTS 2/1970 Place etal.... ..337/99 3/1966 Doyle ..337/99 [4 1 Jan. 16, 1973 1/1966 White ..251/11 2,171,895 4 9/1939 Sardesonm ..73/362.5 2,546,471 3/1951 Myers ..337/378 3,183,719 5/1965 Nonnan et al.... ..73/362.4 3,238,780 3/1966 Doyle ..337/378 X 3,411,711 11/1968 O'Hara et al ..236/87 Primary Examiner-William E. Wayner Attorney-Auzville Jackson, Jr., Robert L. Marben and Candor, Candor & Tassone [57] ABSTRACT A condition responsive pneumatic valve construction having a support means provided with a valve seat means. A plural leg ambient temperature compensating bimetal member has one of the legs thereof provided with a free end means that controls the valve seat means in response to radiant heat directed to such one bimetal leg through an aligned window means in a cover means carried by the support means, the remainder of said legs being secured to said support means at the free end means thereof.

12 Claims, 11 Drawing Figures j IOA PATENTEDJAN 16 1915 3,711,018

' SHEEIl0F4 '6 I BY HIS ATTORNEYS PATENTEDJAH 16 1973 3,711,018 SHEET 3 OF 4 69 FIG. 8 39A j IOA IIA HIS ATTORNEYS 60 INVENTCR.

86 DOUGLAS R. SCOTT PAIENTEDJAN 16 I915 3,711,018

SHEET [1F 4 IOA FIGJH INVENTOR. DOUGLAS R. SCOTT HIS ATTORNEYS VALVE CONSTRUCTION This application is a Continuation-in-Part of its copending parent Pat. application, Ser. No. 815,977, filed Apr. 14, 1969, and is assigned to the same assignee to whom this application is assigned.

This invention relates to a pneumatic control system and to a condition responsive pneumatic valve construction for such a control system or the like.

It is well known from the copending Pat. application, Ser. No. 732,784, filed May 28, 1968, now U.S. Pat. No. 3,522,662, that a pneumatic valve construction can be utilized in a pneumatic control system to interconnect a pneumatic source to a pneumatically operated device as long as the condition responsive means of the pneumatic valve construction is sensing a certain condition of a heating means that is interconnected to an energy source therefor when the pneumatically operated device is interconnected to the pneumatic source. However, when the condition responsive means of the pneumatic valve construction senses another condition of the heating means, the pneumatic valve construction prevents communication between the pneumatic source and the pneumatically operated device to terminate the operation of the heating means.

' It is also well known from U.S. Pat No. 3,338,268 that slide valves for interconnecting a pneumatic source to a pneumatically operated device can be provided wherein the valve member comprises a pair-of thin flexible sheets of material having porous compressible material sandwiched therebetween with one of the sheets being provided with channel means therein for interconnecting two ports in a valve surface togher when such channel means is aligned therewith.

It is a feature of this invention to provide an improved condition responsive pneumatic valve construction for the previously described pneumatic control system or the like.

Another feature of this invention is to utilize the slide valve means of the type disclosed and claimed in the US. Pat. No. 3,338,268 in such improved condition responsive pneumatic valve construction of this invention.

In particular, one embodiment of this invention provides a condition responsive pneumatic valve construction comprising a support means having a valve seat means. A plural leg bimetal member is carried by the support means and has one of its legs controlling the valve seat means in response to certain conditions of the heating means as sensed by the bimetal member.

Accordingly, it is an object of this invention to provide an improved condition responsive pneumatic valve construction having one or more of the novel features set forth above or hereinafter shown or described.

Other objects, uses and advantages of this invention are apparent from a reading of this description which proceeds with reference to the accompanying drawings forming a part thereof and wherein:

FIG. 1 is a top perspective view of one of the improved condition responsive pneumatic valve constructions of this invention.

FIG. 2 is an enlarged, cross-sectional view taken substantially on line 2-2 of FIG. 1.

FIG. 3 is a cross-sectional view taken on line 3-3 of FIG. 2.

FIG. 4 is a view similar to FIG. 3 and illustrates the valve construction of FIG. I in another operating position thereof.

FIG. 5 is a cross-sectional view taken on line 5-5 of FIG. 3 and illustrates schematically the improved control system of this invention.

FIG. 6 is a cross-sectional view taken on line 66 of FIG. 3.

FIG. 7 is a view similar to FIG. I and illustrates another improved condition responsive pneumatic valve construction of this invention.

FIG. 8 is an enlarged top view of the valve construction of FIG. 7 with the cover member and window assembly removed.

FIG. 9 is a cross-sectional view taken on line 9-9 of FIG. 8.

FIG. 10 is a cross-sectional view taken on line '10- 10 of FIG. 8.

FIG. 11 is an exploded perspective view of certain of the parts of the valve construction of FIG. 7.

While the various features of this invention are hereinafter described and illustrated as being particularly adapted to provide control means for a heating means, it is to be understood that the various features of this invention can be utilized singly or in any combination thereof to provide control means for other devices as desired.

Therefore, this invention is not to be limited to only the embodiments illustrated in the drawings, because the drawings are merely utilized to illustrate one of the wide variety of uses of this invention.

Referring now to FIGS. 1-3, one of the improved condition responsive pneumatic valve constructions of this invention is generally indicated by the reference numeral 10 and comprises a housing or support means 11 that is substantially cup-shaped and cooperates with a cover member 12 to define a chamber 13 therebetween.

The housing or support member 11 can be formed of molded plastic material in the configuration illustrated in the drawings wherein an interior flat surface 14 thereof is interrupted by a rectangular slot 15 that defines opposed parallel surfaces 16 and 17, the surface 16 defining a flat valve surface interrupted by a pair of ports 18 and 19 as illustrated in FIG. 6 with such ports 18 and 19 being respectively in fluid communication with passage means 20 and 21 formed through integral nipple extensions 22 and 23 of the housing or support member 11. In this manner, the nipple extension 22 can be coupled to a conduit means 24 that leads from a pneumatic source 25. Similarly, the nipple extension 23 can be coupled to a conduit means 26 that leads to a pneumatically operated device 27.

As illustrated in FIG. 5, the control system of this invention is generally indicated by the reference numeral 28 and includes the condition responsive pneumatic valve construction 10, the pneumatic source 25 and pneumatically operated device 27 previously described aswell as a heating means 29 and an energy source 30 therefor whereby when the pneumatically operated device 27 is interconnected to the pneumatic source 25 in a manner hereinafter described, the pneumatically operated device 27 will interconnect the energy source 30 to the heating means 29 so that the heating means 29 will operate as long as the pneumatically operated device 27 is interconnected to the pneumatic source 25. However, when the pneumatic source 25 is disconnectedfrom the pneumatically operated device 27 by the condition responsive pneumatic valve construction of this invention in a manner hereinafter described, the energy source 30 is disconnected from the heating means 29.

While the heating means 29 and energy source 30 thereof can be conventional means, such as a burner and a fuel source therefor, or an electrical ignition coil and an electrical power source therefor, etc., it is to be understood that the pneumatically operated device 27 operates as a switching means between the. energy source 30 and the heating means 29.

v A slidable valve member 31 is disposed in the rectangular slot of the support means 11 as illustrated in FIG. 3 and comprises two thin and flat flexible plastic sheets 32 and 33 carrying a porous compressible material 34 therebetween so that when the valve member 31 is disposed in the rectangular slot 15, the porous compressible material 34 is compressed between the sheets 32 and 33 so as to urge the sheets 32 and 33 respectively outwardly into sealing engagement with the opposed surfaces 16 and 17 of the support 11. However, the material of the sheets 32 and 33 and the material of the support means 11 are so compatible that the sheets 32 and 33 are readily slidable against their engaging surfaces 16 and 17.

The flexible sheet 32 that is disposed in sliding engagement with the valve surface 16 of the support means 11 has a blister or channel 35 formed therein and facing toward the valve surface 16 so that when the valve member 31 is disposed in the position in FIG. 3 and has its lower end 36 disposed against an end wall 37 of the slot 15, the channel 35 bridges the ports 18 and 19 as illustrated in FIG. 6 so as to fluidly interconnect the pneumatic source with the pneumatically operated device 27.

However, when the valve member 31 is moved upwardly from the position illustrated in FIG. 3 to the position illustrated in FIG. 4 where the channel thereof is out of alignment with the ports 18 and 19, the pneumatic source 25 is disconnected from the pneumatically operated device 27 by the valve member 31. If desired, the flexible sheet 32 can have an aperture 38 passing completely therethrough and in such an arrangement that when the valve member 31 is in the up position illustrated in FIG. 4, the aperture 38 will be aligned with the port 19 so that the pneumatically operated device 27 is fluidly interconnected to the atmospher'e with the porous compressible material 34 filtering any air flow between the pneumatically operated device 27 and the atmosphere.

A substantially U-shaped flat bimetal member 39 is disposed in the chamber 13 of the housing means 11 and has the free end 40 of one leg 41 thereof stepped downwardly from the normal plane thereof and fastened to the flat surface 14 of the housing 11 by suitable fastening means 42. The other leg 43 has a tongue-shaped free end 44 respectively passing through aligned slots 45 and 46 in the flexible sheets 32 and 33 as illustrated in FIGS. 2 and 3 to interconnect the leg 43 to the valve member 31. The yoke portion 47 of the bimetal member 39 has its righthand end 48 angularly bent throughout the length thereof to stabilize the yoke portion 47 for a purpose hereinafter described.

A transverse'wall means 49 having a rounded right end is carried 'by the support means 1 1 and projects upwardly between the legs 41 and 43 in the manner illustrated in FIGS. 2 and 3 so as to tend to prevent heat and light adjacent the leg 43 from reaching the ambient compensating leg 41 of the bimetal member 39.

A rounded extension 50 extends upwardly from the flat surface 14 of the support member 11 and is so constructed and arranged that the leg 43 of the bimetal member 39 engages against the abutment 50 when the leg 43 fully moves the valve member 31 to the position against the end wall 37 of the support 11 as illustrated in FIG. 3 where the valve member 31 is fluidly interconnecting the ports 18 and 19 together by the channel means 35 thereof.

. The cover member 12 is adapted to be secured over the open end 51 of the support member 11 to close the chamber 13 thereof. However, the cover member 12 has a window means 52 formed therethrough which can be closed by suitable transparent material 53 as illustrated, the window means 52 in the cover member 12 being alignable only with the leg 43 of the bimetal member 39 when the cover member 12 is secured to the support member 11 is the manner illustrated in the drawings. I

The condition responsive pneumatic valve construction 10 of this invention is normally arranged relative to the heater means 29 so that direct radiant heat from the heater means 29 can pass through the window means 52 of the cover member 12 directly to the leg-43 of the bimetal member 39 so that the leg 43 will directly sense such radiant heat from the heater 29. However, the cover member 12 and wall means 49 are so arranged relative to the other leg 41 of the bimetal member 39 that the leg4l will not be exposed to direct radiant heat from the heater means 29. 4

The operation of the control system 28 of this invention and the operation of the condition responsive pneumatic valve construction 10 of this invention as utilized in such system 28 will now be described.

When it is desired to operate the heater means 29, the operator turns on the pneumatic source 25, such as by turning on a pneumatic pump or a vacuum pump which comprises the source 25 and since the heater means 29 is not operating, the bimetal member 39 is in the full line configuration of FIG. 3 so as to hold the valve member 31 in its position for fluidly interconnecting the inlet port 18 with the outlet port 19 thereof whereby the pneumatic source 25 will be connected with the pneumatically operated device 27 when the source 25 is turned on.

With the pneumatic source 25 now being interconnected to the pneumatically operated device 27, the pneumatically operated device 27 interconnects the energy source 30 to the heating means 29 so that the heating means 29 begins to operate. When the radiant heat from the heating means 29 that is being directly sensed by the bimetal leg 43 of the bimetal-member 39 reaches a certain limit, the resulting heating of the leg 43 of the bimetal member 39 by the radiant heat causes the leg 43 to warp in an upward direction and since the leg 41 of the bimetal member 39 is not sensing such radiant heat, the yoke portion 47 of the bimetal member 39 remains in the full line position of FIG. 3 so that the free end 44 of the leg 43 warps upwardly as illustrated in FIG. 4 to carry the valve member 31 therewith and thereby move the channel 35 out of alignment with the ports 18 and 19 in the valve surface 16 so as to disconnect the pneumatic source from the pneumatically operated device 27 and, thus, cause the pneumatically operated device 27 to disconnect the energy source 30 from the heating means 29.

By making the facing area of the channel in the valve sheet 32 larger than the inlet port 18 for the pneumatic source 25, a differential pressure is obtained in the channel 35 which tends to resist the movement of the valve member 31 from the position of FIG. 3 to the position of FIG. 4. However, as the bimetal leg 43 is being heated by the radiant heat from the heater 29, the resulting warping of the leg 43 and the storing of energy therein subsequently overcomes such differential pressure so that a somewhat of a snap action occurs to move the valve member 31 from the position of FIG. 3 to the position of FIG. 4.

As previously stated, the aperture 38 formed through the reading sheet 32 of the valve member 31 becomes aligned with the outlet port 19 of the valve surface 16 when the valve member 31 is moved upwardly against the cover member 12 by the bimetal leg 43 having sensed a certain condition of the heating means 29. With the aperture 38 now aligned with the outlet port 19, it can be seen that the pneumatically operated device 27 is directly interconnected to the atmosphere to rapidly deactuate the same so as to disconnect the energy source 30 from the heating means 29.

With the. valve member 31 now in the position illustrated in FIG. 4 so as to cause the termination of the operation of the heating means 29, the bimetal member 43 will subsequently return to the position illustrated in FIG. 3 since the same is no longer sensing any radiant heat from the heater means 29 so that the valve member 31 again interconnects the inlet port 18 with the outlet port 19 and, thus, the pneumatic source 25 with the pneumatically operated device 27 should it be desired to again operate the heating means 29.

With the condition responsive pneumatic valve construction disposed in the position illustrated in FIG. 3, a change in the ambient temperature surrounding the valve construction 10 will not cause the valve member 31 to move because both bimetal legs 43 and 41 sense the ambient temperature change and if the ambient temperature change is an increase in temperature, both legs 41 and 43 will warp upwardly as illustrated in phantom lines in FIG. 3 to carry the yoke end 47 thereof upwardly and not the valve member 31.

In this manner, the unique configuration of the bimetal member 39 completely compensates for any ambient temperature changes surrounding the condition responsive pneumatic valve construction 10 so that such ambient temperature changes will not cause movement of the valve member 31, the movement of the valve member 31 only occurring through the influence of direct radiant heat from the heating means 29 or lack thereof.

Another condition responsive pneumatic valve construction of this invention is generally indicated by the reference numeral 10A in FIGS. 7-11 and parts thereof similar to the condition responsive pneumatic valve construction 10 previously described are indicated by like reference numerals followed by the reference letter A.

As illustrated in FIGS. 7-9, the condition responsive pneumatic valve construction 10A includes a housing or support means 11A that is substantially cup-shaped in the same manner as the housing 11 previously described and cooperates with a cover member or support bracket 12A to define a chamber 13A therebetween. However, in place of the slide valve means 15 of the condition responsive valve construction 10 previously described, a bottom wall 60 of the housing 11A has a threaded bore 61 passing therethrough and threadedly receiving a threaded portion 62 ofa tubular valve seat means 63 having a frustoconical upper end 64 interrupted by a passage means 65 passing completely through the valve seat member 63 to the exterior thereof, the valve seat means 63 having a suitably shaped portion 66 for grasping the valve seat member 63 and rotating the same relative to the housing 11A to position the valve seat end 64 relative to the housing 1 1A at the desired position thereof.

The passage 64 of the valve seat means 63 can be interconnected by a conduit 66 to a pneumatic source 25A, such as a vacuum pump or the like, as well as by a branch conduit 67 toa pneumatically operated device 27A which, when effectively interconnected to the vacuum source 25A, will interconnect the energy source 30A to the heating means 29A whereby the pneumatic system 28A of FIG. 9 is substantially the same as the pneumatic system 28 of FIG. 5 previously described. However, when the conduit 66 is vented to the atmosphere in a manner hereinafter described by the condition responsive pneumatic valve construction 10A of this invention, even through the pneumatic source 25A is still interconnected to the conduit 66, the effect of the pneumatic source 25A on the control means 27A is such that the control means 27A will prevent the energy source 30A from being interconnected to the heating means 29A. Thus, only when the conduit means 66 is disconnected from the atmosphere will the pneumatic source 25A be sufficiently effective to actuate the operator 27A so that the operator 27A can interconnect the energy source 30A to the heating means 29A.

The plural leg bimetallic member 39A of the valve construction 10A is a three legged bimetal member with the two outboard legs 68 and 69 thereof being substantially flat and coplanar with each other throughout their length and being shorter than the coplanar and parallel middle leg 70, the legs 68, 69 and 70 each being integrally joined together at the right hand ends thereof in FIG. 8 by a coplanar yoke portion 71 of the bimetallic member 39A which is suitably bent at right angles at the free edge 72 thereof to stabilize the yoke portion 71 in a manner similar to the yoke portion 47 of the bimetallic member 39 previously described.

The free end means 73 and 74 of the outboard legs 68 and 69 of the bimetal member 39A have openings 75 and 76 respectively passing therethrough so as to permit suitable rivet-like fastening means 77 to rivet or otherwise secure the free end means 73 and 74 of the legs 68 and 69 to the housing means 11A in the manner illustrated in FIGS. 8 and 9.

The housing means 11A is so constructed and arranged that the same defines wall means 78 and 79 disposed in the bight portions 80 and 81 respectively disposed between the outboard leg 68 and the middle leg 70 and the middle leg 70 and the outboard leg 69 for the same purpose as the wall means 49 previously described whereby the window means 52A in the cover member 12A is located only over the middle leg 70 so the middle leg 70 will sense the radiant energy being passed through the window 53A for the same purpose as the leg 43 of the valve construction 10 previously described.

The free end means 82 of the middle leg 70 of the bimetallic member 39A comprises another bimetallic member 83 secured thereto by spot welding or the like with the other bimetallic member 83 having an opening 84 passing therethrough and being alignable with the valve'seat end 64 of the valve seat means 63 for a purpose hereinafter described and fully illustrated in FIGS. 8 and 9.

The bimetallic member 39A is formed in such a manner that the upper side of the legs 68, 69 and 70 thereof comprise the low expansion side thereof while the other side thereof is the high expansion side thereof. Conversely, the bimetallic member 83 forming the free end means 82 of the leg 70 has its high expansion side facing upwardly in FIG. 8 and its low expansion side facing downwardly toward the valve seat means 63. Also, the bimetallic member 83 is thinner than the leg 70 so as to be livelier for a purpose hereinafter described.

In this manner, upon the sensing of radiant heat through the window 52A of the cover member 12A of the valve construction 10A, the leg 70 will warp upwardly while the extension 83 thereof will warp downwardly and subsequently the valve seat 64 will be fully opened and interconnect the chamber 13A to the conduit 66 and since the chamber 13A is adapted to be vented to the atmosphere through a vent opening 85 in the end wall 60 of the housing means 11A, the atmosphere is adapted to enter through suitable filtering material 86 and the vent opening 85 into the chamber 13A to prevent the vacuum source 25A from operating the pneumatically operated actuator 27A for the reasons previously set forth.

A resilient cap or pad is adapted to be slipped over the end of the bimetal member 83 so as to cover the opening 84 thereof on opposed sides thereof whereby such resilient member 87 will cushion against the end 64 of the valve seat member 63 to fully seal close the same as the opening 84 in the bimetal member 83 is concentric with the upper end 64 of the valve seat 63 in the manner illustrated in FIG. 8.

Thus, it can be seen that the valve construction 10A of this invention functions in a manner similar to the valve construction 10 previously described except that a three-legged bimetallic member 39A is being utilized and the same is opening and closing the valve seat means 63 by merely an engagement thereagainst as opposed to operating a slide valve means 15 as in the valve construction 10 previously described.

However, it was previously pointed out that the slide valve means 15 of the valve construction 10 previously described acts with a snap-action when the same moves from the position illustrated in FIG. to the position illustrated in FIG. 4 to terminate the operation of the device 29. This snap-action effect is to provide the valve construction with a differential action in the operation of the heating device 29.

Such snap-acting effect is not necessary in the valve; construction 10A because of the lively and reverse acting bimetal portion 83 of the middle leg 70 of 'the bimetal member 39A.

In particular, with the valve construction 10A disposed in the position illustrated in FIG. 9 where the valve seat 64 is closed, the pneumatic source 25A operates the device 27A so that the energy source 30A is interconnected to the device 29A whereby thedevice 29A is operating and the radiant energy thereby is being sensed by the valve construction 10A through the window means 53A. Such radiant energy from the device 29A causes the lively reverse acting bimetal portion 83 to warp or bend downwardly and thereby force the valve head 87 downwardly against the valve seat 64 to maintain the valve seat 64 fully closed while the longer and thicker section 70 of the bimetal member 39A begins to slowly warp or move upwardly. Eventually, the slower moving, but longer central leg portion of the bimetal member 39A moves through a distance sufficient to lift the downwardly deflected reverse acting bimetal portion 83 and thereby raise the valve pad 87 off of the valve seat 64 to open the valve seat 64. When the valve pad 87 leaves the valve seat 64 to open the same, the radiation source 29A is deenergized because the active effect of the pneumatic source 29A on the device 27A ceases to exist as previously described so the energy source 30A is disconnected from the device 29A. This deenergizing of the radiation source 29A permits the lively bimetal portion 83 to quickly return to its original non-warped position whereas the heavier bimetal portion 70 of the bimetal member 39A slowlyreturns to its original position to cause closing of the valve seat 64 so that the overall effect of the operation is to provide the valve construction 10A with a differential in the opening and closing of the valve seat 64 without the need for conventional snap-acting mechanisms.

For example, if the central leg 70 were not provided with the reverse acting, lively bimetal member 83, initial radiation on the central leg 70 by the device 29A would cause the valve disc 87 to leave the valve seat 64 to immediately deenergize the radiation source 29A causing the valve disc 87 to return to the seat 64 and reenergize the radiation device 29A. Under such conditions, the valve disc 87 merely sits adjacent the valve seat 64 and repetitively kisses the same making the radiation source 29A just warm enough to hold it there and if the radiation source 29A is a fuel igniter, the same would not get hot enough to ignite fuel. In contrast, when a differential is built into the valve construction 10A by the lively reverse acting bimetal member 83, the device 10A can cause the device 29A to reach the required 1800 F for fuel igniting purposes.

By way of example and not limitation on this invention, the leg 70 of the bimetal member 39A can be approximately 0.0l5 of an inch thick whereas the lively bimetal member 83 can be approximately 0.010 of an inch thick with the leg 70 and bimetal member 83 both having a width of approximately 0.250 of an inch. The bimetal member 83 can have a length of approximately 0.500 of an inch and the leg 70 from the yoke portion 72 thereof can have a length of approximately 1.000 inch.

Accordingly, it can be seen that this invention not only provides a control system having an improved condition responsive pneumatic valve means, but also this invention provides an improved condition responsive pneumatic valve construction or the like.

While the form of the invention now preferred has been described and illustrated by the patent statutes, other forms may be utilized all coming within the scope of the claims that follow.

What is claimed is:

l. A condition responsive pneumatic valve construction comprising a support means having valve seat means, and a substantially flat three-legged bimetal member having the three legs thereof disposed substantially parallel to each other and being joined in spaced apart relation at adjacent ends by a yoke portion of said bimetal member, one of said legs having free end means so constructed and arranged that the same controls said valve seat means, the other of said legs having free end means respectively interconnected to said support means to support said bimetal member to said support means, said free end means of said one leg of said bimetal member carrying resilient means for engaging against said valve seat means to close the same, said free end means of said one leg of said bimetal member having an opening passing therethrough that is alignable with said valve means, said resilient means covering said opening, said resilient means comprising a cap-like member telescopically disposed over the free end means of said one leg of said bimetal member to cover both sides of said opening respectively at both sides of said free end means. i

2. A condition responsive pneumatic valve construction as set forth in claim 1 wherein said yoke portion of said bimetal member has a free end thereof extending across the width of the same and being bent out of the plane of the remainder of said yoke portion to stabilize said yoke portion.

3. A condition responsive pneumatic valve construction as set forth in claim l wherein said one leg of said bimetal member is the middle leg of said three-legged. bimetal member.

4. A condition responsive pneumatic valve construction as set forth in claim 3 wherein said free end means of said one leg extends from said yoke portion a greater distance than the distance said free end means of said other legs extend from said yoke portion.

5. A condition responsive pneumatic valve construction as set forth in claim 3 wherein said other legs of said bimetal member act as ambient temperature compensators for said valve construction.

6. A condition responsive pneumatic valve construction as set forth in claim 3 wherein a cover member is carried by said support means and has window means therein, said window means being aligned with said one leg of said bimetal member so said one leg is responsive to radiant heat directed through said window means, said cover member preventing said radiant heat from being directed to said other legs of said bimetal member.

7. A condition responsive pneumatic valve construction as set forth in claim 6 wherein said support means has wall means projecting through the bights between said one leg and said other legs of said bimetal member to shield said other legs of said bimetal member from heat and lightadjacent said one leg thereof.

. A condition responsive pneumatic valve construction as set forth in claim 1 wherein said free end means of said one leg of said bimetal member comprises another bimetal member secured to said one leg of said three-legged bimetal member.

9. A condition responsive pneumatic valve construction as set forth in claim 8 wherein the low expansion side of said three-legged bimetal member faces in one direction and the low expansion side of said other bimetal member faces in the opposite direction.

10. A condition responsive pneumatic valve construction as set forth in claim 9 wherein said low expansion side of said other bimetal member faces toward said valve seat means.

11. A condition responsive pneumatic valve construction as set forth in claim 1 wherein said valve seat means comprises a tubular member adjustably carried by said support means.

12. A condition responsive pneumatic valve construction as set forth in claim 1 wherein said support means defines a chamber having said bimetal member and said valve seat means therein, said support means having a vent opening interconnecting the exterior of said support means to said chamber. 

1. A condition responsive pneumatic valve construction comprising a support means having valve seat means, and a substantially flat three-legged bimetal member having the three legs thereof disposed substantially parallel to each other and being joined in spaced apart relation at adjacent ends by a yoke portion of said bimetal member, one of said legs having free end means so constructed and arranged that the same controls said valve seat means, the other of said legs having free end means respectively interconnected to said support means to support said bimetal member to said support means, said free end means of said one leg of said bimetal member carrying resilient means for engaging against said valve seat means to close the same, said free end means of said one leg of said bimetal member having an opening passing therethrough that is alignable with said valve means, said resilient means covering said opening, said resilient means comprising a cap-like member telescopically disposed over the free end means of said one leg of said bimetal member to cover both sides of said opening respectively at both sides of said free end means.
 2. A condition responsive pneumatic valve construction as set forth in claim 1 wherein said yoke portion of said bimetal member has a free end thereof extending across the width of the same and being bent out of the plane of the remainder of said yoke portion to stabilize said yoke portion.
 3. A condition responsive pneumatic valve construction as set forth in claim 1 wherein said one leg of said bimetal member is the middle leg of said three-legged bimetal member.
 4. A condition responsive pneumatic valve construction as set forth in claim 3 wherein said free end means of said one leg extends from said yoke portion a greater distance than the distance said free end means of said other legs extend from said yoke portion.
 5. A condition responsive pneumatic valve construction as set forth in claim 3 wherein said other legs of said bimetal member act as ambient temperature compensators for said valve construction.
 6. A condition responsive pneumatic valve construction as set forth in claim 3 wherein a cover member is carried by said support means and has window means therein, said window means being aligned with said one leg of said bimetal member so said one leg is responsive to radiant heat directed through said window means, said cover member preventing said radiant heat from being directed to said other legs of said bimetal member.
 7. A condition responsive pneumatic valve construction as set forth in claim 6 wherein said support means has wall means projecting through the bights between said one leg and said other legs of said bimetal member to shield said other legs of said bimetal member from heat and light adjacent said one leg thereof.
 8. A condition responsive pneumatic valve construction as set forth in claim 1 wherein said free end means of said one leg of said bimetal member comprises another bimetal member secured to said one leg of said three-legged bimetal member.
 9. A condition responsive pneumatic valve construction as set forth in claim 8 wherein the low expansion side of said three-legged bimetal member faces in one direction and the low expansion side of said other bimetal member faces in the opposite direction.
 10. A condition responsive pneumatic valve construction as set forth in claim 9 wherein said low expansion side of said other bimetal member faces toward said valve seat means.
 11. A condition responsive pneumatic valve construction as set forth in claim 1 wherein said valve seat means comprises a tubular member adjustably carried by said support means.
 12. A condition responsive pNeumatic valve construction as set forth in claim 1 wherein said support means defines a chamber having said bimetal member and said valve seat means therein, said support means having a vent opening interconnecting the exterior of said support means to said chamber. 